Right now, there’s no consensus (general agreement) among experts who study low back pain in an effort to prevent repeat episodes. The definition of low back pain recurrence can range anywhere from the patient’s pain returned to the patient had at least a month without back pain before the pain returned and lasted for more than 24 hours.
According to some experts, a true recurrence really means the patient recovered fully from the first episode. The new symptoms are truly considered a separate incident. But the gray area comes when trying to say just when one episode ended and a new episode began. And there’s some question as to whether features such as pain intensity, duration, or frequency should factor into the definition.
As you have discovered, persistence of pain from a first episode that never really recovered is different from recurrence. Persistence of pain occurs in someone who did not recover from the first bout of low back pain. Clear, separated pain episodes are used to distinguish recurrence from a continuation of the original pain.
According to the most recent studies, to qualify as a separate episode, back pain must occur after at least 30 painfree days after the original episode of back pain. This last parameter (i.e., pain-free for at least one month) represents the working definition of recovery.
Ask your doctor to help you sort out what parts of your clinical picture and history might support that what you experienced amounted to two separate episodes.